1. Field of the Invention
The present invention relates to an apparatus for limiting the use of a particular network address.
2. Description of the Related Art
Personal computers and workstations supporting IPv6 typically use Ethernet® for the network connection interface, and generate an IPv6 address based on the Ethernet® IEEE identifier (MAC address). Hereinafter, an address generated in the manner described above is called an IEEE EUI-64 IPv6 address.
As described later, there are three types of IPv6 address: link-local addresses, site-local addresses, and (aggregatabale) global addresses.
The IPv6 addressing scheme is described in detail in the following documents:                Request for Comment (RFC) 2373 IP Version 6 Addressing Architecture,        RFC 2374 An IPv6 Aggregatabale Global Unicast Address Format,        RFC 2375 IPv6 Multicast Address Assignment,        RFC 2450 Proposed TLA and NLA Assignment Rule,        RFC 2461 Neighbor Discovery for IP Version 6 (IPv6), and        RFC 2462 IPv6 Stateless Address Autoconfiguration.        
IEEE EUI-64 IPv6 addresses of network devices are generated based on the IEEE identifiers (i.e., MAC addresses) of the hardware interfaces (e.g., Ethernet®) used in the network devices, where each hardware interface has a unique IEEE identifier. This approach readily leads to privacy infringement of a network device or the user of the network device, because the activities can easily be identified by monitoring communication involving the IEEE EUI-64 IPv6 address of the network device.
To overcome this problem, procedures for generating random IPv6 addresses, specifically interface IDs, are proposed in, for example, RFC 3041 Privacy Extensions for Stateless Address Autoconfiguration in IPv6. This document also describes a protocol, and its extension, for detecting whether or not a generated random value is already used and, if used, generating another unique random address. This random IPv6 address is called a temporary address or anonymous address.
Not all devices may use an anonymous address. Some devices may be initialized to use an IEEE EUI-64 IPv6 address. Therefore, these devices may be subject to privacy infringement if the IEEE EUI-64 IPv6 address is used continuously.